Apparatus for indicating the presence of dangerous gases.



Patented .mnh 4V lem.

' H. G. -PRESTEIL APPARATUS FOB INDIGATIIG'I'HE PRESEMGEIUF DANGEROUS GASES.

(Application lod Oct. 15, 1900.)

-Uln' lodol.)

a 'il 6 Yu: nonms Fc'rzns co, PNoTaurHa. wnsume'rcn. n, c.

` UNITED STATES PATENT OFFICE. i

HENRY G. PRESTED, OF LONDON, ENGLAND.

APPARATUS FR INDICATING THE PRESENCE 0F DANGEROUS GASES.

SPECIFICATION formingpart of Letters Patent No. 675,755, dated June 4, 190'1.

Application filed October 15, 1900. Serial No. 33,124. (No model.)

To all whom it may concern:

Be it known that I, HENRY GEORGE PRES- TED, a citizen of England, residing at No. 44 Brecknock r-oad, Camden Town, London, England, have invented certain new and useful Improvements in Apparatus for'lndicating the Presence of Dangerous Gases, (for which I have applied for a patent in Great Britain, dated March 17, 1900, No. 5,1250 of which the following is a specification.

Apparatus have been proposed for indicating the presence of explosive gases in mines and elsewhere based on the following principle: A porous vesselwhen exposed to such gases allows passage of the gas inward more rapidly than passage outward of the air contained in the vessel, as the gas and air tend to diffuse, and thus a exible diaphragm closing a passage from the vessel vbecomes more or lessbul ged and makes an electrical contact whereby an alarm is operated.

My invention relates `to an apparatus acting on ,this principle,'comprising a porous vessel with flexible diaphragm, a battery, and a glowlamp connected with thebattery through a contact adjustable by a delicate screw, the point of which nearly` meets a small platinum plate fixed on the flexible diaphragm, the distance between the points of Contact being set to correspond with such percentage of explosive mixture as it may be desired to detect, When this percentage is reached, the diaphragm is bulged so that contact is made and the small lamp is lighted. The diaphragm and contact-screw are inclosed in an airtight chamber, so that no spark at break of contact can ignite the surrounding explosiveatmosphere.

The apparatus can be applied for indicating the presence of choke-damp or gas denser than air, in which case the diaphragm is bulged in- Ward and not outward,'breaking contact and extinguishing the lamp.

Instead of employing a vessel having its whole surface porous I find it is better to employ one which has considerable capacity, but has a considerable part of its surface rendered impervious by coating it with wax or other suitable material.

The accompanying drawingis an elevation,

partly in section, showing on a considerably enlarged scale apparatus according to my invention.

a is the porous vessel, having a plug b,

.through which passes a tube c, leading to the flexible diaghragm d, having fixed on its center a piece of platinum electrically connected to one of the wires e, leading to a glow-lamp g, the other wiref of which is connected to one pole of a battery h. The other pole of the battery is connected by a wire t' to the nut j of a platinum-pointed adjusting-screw k., this nut being held in a plug Z, of insulating man terial, tted in the chamber. On the screw' is fixed a graduated disk m, so that when the screw is turned any division on the disk may be brought around to a fixed index n'.

The diaphragm and end of the contact-screw' are inclosed in an air-tight chamber, so that no spark can ignite the surrounding atmosphere should it be combustible and no resisting substance can enter to interfere with the contacts.

The porous vessel may have its surface 'coated with impervious rmaterial to a greater or less extent, according as the apparatus is intended to be less or more sensitive or rapid in its indications and the contact-screw lc' is adjusted more or less near the diaphragm.

When by the entrance of a gas lighter than air more rapidlyinto the vessel than air issues from it the diaphragm d is bulged, so that its platinum makes contact with the screw' 7o, then the lamp g becomes lighted, apprising the observer that the apparatus is in an at' mosphere which may be explosive.

The same apparatus may be employed to in dicate ther presence of gas heavier than air, such as choke-damp. For this purpose the screw 7o is advanced to make contact with the platinum on the diaphragm, the lamp g being thus lighted. As air issues more rapidly from the vessel a than the heavier gas enters, theA diaphragm d becomes bulged inward, leaving the screw k, so thatV the lamp g becomes extinguished, showing the presence of the ch0ke= damp.

Having thus described the nature of this invention andthe best means I know for carry-- ing the same into practical effect, I claim-,-

In an apparatus of the class specified, aportricaily connected respectively-with said 4diaous vessel having a plug at its'lower end, a,l phragm and screw, the eonnectionsine'luding tube extending through said plug, a exibie a signal. diaphragm at the outer end of the tube, hav- It testimony whereof I havehereunto set 5 ing a piece of platinum on its outer face, a my hand `in presence of two subscribing wit- I5 chamber surrounding the diaphragm having nesses.

a plug of insulating 4material in one end of HENRY G. PRES'IED. the same, a nut fitted in said last-mentioned Witnesses: plug, a serew passing through said nut, \hav OLIVER IMRAY,

ro inga platinum point\,aud a' battery elec- GERALD. L. SMITH. 

